Multi-speed transmission in planetary design

ABSTRACT

A planetary multi-speed transmission with a housing is proposed for a vehicle. A first shaft is provided as a drive and a second shaft is provided as an output, axially parallel to the drive. Three planetary gear sets and additional shafts, along with six shifting elements, are provided, through which the actuation of several gears can be realized. Machine elements are provided for the transfer of torque between the drive and the output. The first shaft is connectable, as the drive, to the sun gear of the second planetary gear set, to the sun gear of the first planetary gear set, to the planetary gear carrier of the second planetary gear set, to the planetary gear carrier of the first planetary gear set, and to the first machine element. The second shaft is connected or connectable, as a drive, to the first machine element and to the second machine element.

FIELD OF THE INVENTION

The present invention relates to a multi-speed transmission in planetary design for a vehicle having a transmission housing, whereas a first shaft is provided as a drive and a second shaft is provided as an output that is arranged in a manner axially parallel to the drive, whereas three planetary gear sets and additional shafts along with six shifting elements are provided, through which the actuation of several gears can be realized, and whereas machine elements are provided for the transfer of torque between the drive and the output.

BACKGROUND

As an example, publication DE 10 2007 014 150 A1 discloses a load-shiftable multi-speed transmission. With the multi-speed transmission, the drive shaft is firmly connected through a torsional vibration damper to a first shaft of a first shaft train. A second shaft train arranged parallel to this includes, among other things, the two output shafts designated as shafts. The two shaft trains are connected to each other through three spur gear stages. A first three-shaft planetary gear stage is located on the first shaft train. A second planetary gear stage and a third planetary gear stage are located on the second shaft train. Thus, the multi-speed transmission comprises ten shafts that are connected to each other through three spur gear stages and three planetary gear stages. For shifting the eight forward gears and one reverse gear, five shifting elements are necessary. The provided shifting elements are hydraulically operated.

In order to reduce hydraulic losses, the shifting elements are to be arranged in a manner that is easily accessible from the outside. However, with a front-transverse installation of the transmission in a vehicle, only a limited axial installation space is available.

SUMMARY OF THE INVENTION

The present invention is subject to the task of providing a multi-speed transmission with the highest possible number of gears and an easy accessibility of the shifting elements, with, at the same time, a good gearing efficiency and a need for axial installation space that is as low as possible. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

This task is solved by the transmission embodiments described and claimed herein.

Accordingly, a load-shiftable multi-speed transmission in planetary design, or a multiple-gear planetary transmission for a vehicle with a housing, is proposed, whereas the drive or the drive shaft, as the case may be, and the output or the output shaft, as the case may be, are arranged in a manner axially parallel to each other for a preferred front-transverse installation. The multi-speed transmission in accordance with the invention comprises only nine shafts, three planetary gear sets and only six shifting elements, in order to realize at least nine forward gears and one reverse gear. In addition, for the coupling of the drive and the output, it is preferable that only two machine elements are provided.

Given the fact that the first shaft, as a drive, is detachably connected or connectable to the sun gears of the first and second planetary gear sets, to the first planetary gear set and to the planetary gear carriers of the first and second planetary gear sets and to the first machine element, and that the second shaft, as an output, is connected, or is detachably connected or connectable, to the first machine element and to the second machine element, a multi-speed transmission in accordance with the invention that enables an actuation of the shifting elements that improves the degree of efficiency and is thus in line with demand arises, whereas the advantageously low number of transmission elements of the multi-speed transmission for a front-transverse design has its transmission elements nested with each other in such a manner that an arrangement that particularly saves axial installation space is enabled. In addition to the improved degree of efficiency, low component stresses and low construction costs arise.

The easy accessibility of the shifting elements may be realized, among other things, on the one hand through the use of brakes as shifting elements and, on the other hand, through the use of clutches as shifting elements, which are preferentially positioned at outside shafts, preferably at the drive and at the output, with the multi-stage transmission in accordance with the invention. Due to the low construction costs, in an advantageous manner, low production costs and a low weight of the multi-speed transmission in accordance with the invention arise.

Within the framework of a possible embodiment of the invention, it can be provided that, as a machine element for the coupling or for the transfer of torque between the drive and the output, at least one spur gear stage or the like, which realizes the transmission ratio for the output differential, is used. Preferably, only two machine elements or spur gear stages are provided. However, other machine elements for the transmission of power, such as chains, belts or the like, may be used.

Viewed in an axial direction, the planetary gear sets are arranged in the order of first planetary gear set, second planetary gear set and third planetary gear set, whereas it is preferable that two of the planetary gear sets are designed as negative planetary gear sets and at least one of the planetary gear sets is designed as a positive planetary gear set. However, at spots where the binding ability allows it, individual or several negative planetary gear sets may be converted into positive planetary gear sets, if, at the same time, the bar connection or planetary gear carrier connection and the ring gear connection are exchanged, and the amount of the stationary transmission ratio is increased by the value of 1. As is well-known, a negative planetary gear set features, at the planetary gear carrier, rotatably mounted planetary gears, which mesh with the sun gear and the ring gear of such planetary gear set, such that, with a planetary gear carrier that is held down and a rotating sun gear, the ring gear rotates in a direction opposite to the direction of rotation of the sun gear. As is well-known, a positive planetary gear set features, at its planetary gear carrier, inner and outer planetary gears that are rotatably mounted and are in a tooth meshing with each other, whereas the sun gear of such planetary gear set meshes with the inner planetary gears, and the ring gear of such planetary gear set meshes with the outer planetary gears, such that, with a planetary gear carrier that is held down and a rotating sun gear, the ring gear rotates in the same direction as the direction of rotation of the sun gear.

Within the framework of a particular embodiment of the invention, it can be provided that several of the planetary gear sets are arranged radially relative to each other. For the coupling of the two planetary gear sets, for example, the ring gear of the inner planetary gear set and the sun gear of the outer planetary gear set are designed as one component. For this purpose, for example, the ring gear of the inner planetary gear set features an inner toothing and an outer toothing, but other embodiments are conceivable. Regardless of the type of coupling, the planetary gear sets that are nested in one another are essentially arranged in one axial plane, such that, in an advantageous manner, axial installation space is saved.

With the multi-speed transmission in accordance with the invention, a hydrodynamic torque converter or a hydrodynamic clutch can be used as the start-up element. It is also conceivable that an additional start-up clutch or an integrated start-up clutch or a start-up brake are used. Furthermore, it is possible that an electric machine or any other power source is arranged at at least one of the shafts. Moreover, at at least one of the shafts, a freewheel is arranged for the housing or for another shaft.

Preferably, with the multi-speed transmission in accordance with the invention, nine forward gears and at least one reverse gear can be shifted by means of the provided shifting elements. However, it is conceivable that, for the fourth forward gear (for example), additional shifting combinations are made possible by combining other shifting elements.

The term “shifting element” is understood to mean a shiftable connection between two elements of the transmission, whereas the torque to be transferred between such two elements is transferred by means of the force closure or frictional closure or by means of the form closure. If both elements of the shiftable connection are designed to rotate, the shifting element is referred to as a clutch, and if only one of the two elements of the shiftable connection rotates, the shifting element is referred to as a brake. Moreover, the geometric position and/or order of the individual shifting elements can be freely selected, as long as the binding ability of the elements allows this. In this manner, individual elements may be arbitrarily moved into any position. In addition, to the extent permitted by the external shape, several gear sets can be arranged radially above one another, thus in a nested manner.

Embodiments of a force-fitting shifting element include multi-disk clutches or brakes, band brakes, cone clutches or brakes, electromagnetic clutches, magnetic powder clutches and electro-rheological clutches. Embodiments of a positive-locking shifting element include claw clutches or brakes and tooth clutches.

Thus, in general, both frictional-locking and positive-locking shifting elements may be used as shifting elements. Preferably, given their characteristics, in particular the second shifting element designed as a clutch and the fourth shifting element designed as a clutch can be designed as claw shifting elements, by which significant consumption advantages can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the present invention is explained in more detail based on the drawing. The following is shown:

FIG. 1 is a schematic view of a first design variant of a multi-speed transmission in accordance with the invention;

FIG. 2 is a schematic view of a second design variant of the multi-speed transmission; and

FIG. 3 is a shifting diagram for the various design variants of the multi-speed transmission.

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

Each of FIGS. 1 and 2 shows an example of a design variant of the multi-speed transmission in planetary design in accordance with the invention, for example as an automatic gearbox or automatic transmission for a vehicle.

Regardless of the particular design variants, the multi-speed transmission comprises a merely schematically indicated housing 11, with a first shaft 1 as a drive An and a second shaft 2 as an output Ab that is arranged in a manner axially parallel to the drive, along with seven additional shafts 3, 4, 5, 6, 7, 8, 9. Furthermore, a first planetary gear set RS1, a second planetary gear set RS2 and a third planetary gear set RS3 are provided. For shifting several gears, a first shifting element K1 designed as a clutch, a second shifting element K2 designed as a clutch, a third shifting element K3 designed as a clutch, a fourth shifting element K4 designed as a clutch, a fifth shifting element B1 designed as a brake, and a sixth shifting element B2 designed as a brake are provided. For the coupling or for the transfer of torque between the drive An and the output Ab, two arbitrary machine elements are preferably provided; with the design variants, these are designed, for example, as a first spur gear stage ST1 and a second spur gear stage ST2.

With the first design variant in accordance with FIG. 1, the first spur gear stage ST1 comprises a fixed gear 12, which is connected to the fifth shaft 5, and an idler gear 13 meshing with the fixed gear 12, which is connectable through the ninth shaft 9 and the fourth shifting element K4 to the second shaft. The second spur gear stage ST2 comprises a fixed gear 14, which is connected through the sixth shaft 6 to the ring gear HR3 of the third planetary gear set RS3, and a fixed gear 15 meshing with the fixed gear 14, which is connected to the second shaft 2. In contrast to the first design variant, with the second design variant in accordance with FIG. 2, the first spur gear stage ST1 comprises an idler gear 12A, which is connected through the ninth shaft 9 to the fourth shifting element K4, and a fixed gear 13A, which is connected to the second shaft 2.

With respect to the connection options between the provided shafts 1, 2, 3, 4, 5, 6, 7, 8, 9, the provided three planetary gear sets RS1, RS2, RS3, the provided housing 11 and the provided shifting elements K1, K2, K3, K4, B1, B2 along with the provided spur gear stages ST1, ST2, the term “connectable” is understood to mean that the described elements are detachable (for example, connected by a shifting element), such that the connection is locked with an activated shifting element and open with a non-activated shifting element. The detachable connection may be realized through, in addition to the shifting element, an additional element such as a shaft or the like. The term “connected” is understood to mean that the described elements are connected to each other in a manner that is virtually fixed, thus not detachable. A direct or indirect connection (for example, through additional elements) may be realized.

In accordance with the invention, it is provided with the multi-speed transmission that the first shaft 1 is detachably connected or connectable, as drive An, to the sun gear SR2 of the second planetary gear set RS2, to the sun gear SR1 of the first planetary gear set RS1, to the planetary gear carrier PT2 of the second planetary gear set RS2, to the planetary gear carrier PT1 of the first planetary gear set RS1 and to the first machine element or to the first spur gear stage ST1. Depending on the design variant, the second shaft is connected, or detachably connected or connectable, as output Ab, to the first machine element or to the first spur gear stage ST1, as the case may be, and to the second machine element or the second spur gear stage ST2, as the case may be.

With the first design variant in accordance with FIG. 1, the second shaft 2 is connected to the fixed gear 15 of the second spur gear stage ST2. Furthermore, the second shaft 2 is connectable or detachably connected to the fourth shifting element K4 designed as a clutch and through the ninth shaft 9 to the idler gear 13 of the first spur gear stage ST1.

With the second design variant in accordance with FIG. 2, the second shaft 2 is directly connected to the fixed gear 13A of the first spur gear stage ST1 and to the fixed gear 15 of the second spur gear stage ST2. The idler gear 12A of the first spur gear stage is detachably connected or connectable through the ninth shaft 9 and through the fourth shifting element K4 designed as a clutch, and through the fifth shaft 5 and through the third shifting element K3 designed as a clutch, to the first shaft 1. Furthermore, the first spur gear stage ST1 is connectable through the ninth shaft 9 and through the fourth shifting element K4 designed as a clutch, and through the fifth shaft 5, to the planetary gear carrier PT1 of the first planetary gear set RS1.

With the equally effective transmission variant in accordance with FIG. 2, the fourth shifting element K4 designed as a clutch, which connects the first spur gear stage or the first pair of spur gears ST1 to the output shaft or to the second shaft 2, is held on the other side of the spur gear, thus on the side of the transmission input shaft or the first shaft 1. For this purpose, the original fixed gear 12 is the idler gear 12A and the original idler gear 13 is the fixed gear 13A.

With the multi-speed transmission in accordance with the invention, regardless of the design variant, the first shaft 1 is connectable through the first shifting element K1 designed as a clutch and through the third shaft 3 to the sun gear SR2 of the second planetary gear set RS2, whereas the sun gear SR2 of the second planetary gear set RS2 is connectable through the third shaft 3 and through the sixth shifting element B2 designed as a brake to the housing 11. Furthermore, the first shaft 1 is connectable through the second shifting element K2 designed as a clutch and through the fourth shaft 4 both to the sun gear SR1 of the first planetary gear set RS1 and to the planetary gear PT2 of the second planetary gear set RS2, whereas the sun gear SR1 of the first planetary gear set RS1 and the planetary gear carrier PT2 of the second planetary gear set RS2 are connected to each other through the fourth shaft 4. Moreover, the first shaft 1 is connectable through third shifting element K3 designed as a clutch and through the fifth shaft 5 both to the fixed gear 12 of the first spur gear stage ST1 and the planetary gear carrier PT1 of the first planetary gear set RS1.

Regardless of the particular design variant, the fixed gear 14 of the second spur gear stage ST2 is connected through the sixth shaft 6 to the ring gear HR3 of the third planetary gear set RS3. Furthermore, the ring gear HR1 of the first planetary gear set RS1 is connected through the seventh shaft 7 to the planetary gear carrier PT3 of third planetary gear set RS3.

With the design variants shown, the first planetary gear set RS1 and the third planetary gear set RS3 are each designed as negative planetary gear sets, and the second planetary gear set RS2 is designed as a positive planetary gear set. Furthermore, the second planetary gear set RS2 and the third planetary gear set RS3 are arranged in a nested manner, radially above one another in an axial plane. Thereby, the second planetary gear RS2 is arranged radially inwardly, and the third planetary gear RS3 is arranged radially outwardly with the radially nested gear sets, whereas the two nested gear sets RS2, RS3 are connected to each other through the ring gear HR2 of the second planetary gear set RS2, which at the same time functions as the sun gear of the third planetary gear RS3. The ring gear HR2 of the second planetary gear set RS2 is connectable through the eighth shaft 8 and through the fifth shifting element B1 designed as a brake to the housing 11.

FIG. 3 shows a shifting diagram or a shifting matrix, as the case may be, for the two equally effective transmission variants in accordance with FIGS. 1 and 2. In the shifting diagram, for the realization of the various gears, shifting elements K1, K2, K3, K4, B1, B2 to be locked or activated, as the case may be, are shown in table form, whereas a transmission ratio i is indicated for each gear and the respective gear jump φ is indicated between different gears. In addition to the nine forward gears G1, G2, G3, G4, G5, G6, G7, G8, G9 and the specified reverse gear R, additional shifting combinations are indicated as alternative fourth forward gears M1, M2, M3. As a whole, it also arises from the shifting diagram that the proposed multi-speed transmission features optimized transmission ratio sequences with low absolute and relative rotational speeds and low torques for the planetary gear sets and shifting elements. In addition, good degrees of toothing efficiency and low drag torques arise from the selected arrangements of the gear sets.

As preferred stationary transmission ratios, a value of approximately i₀=−3.450 can be used for the first planetary gear set RS1, a value of approximately i₀=−1.950 can be used for the second planetary gear set RS2, a value of approximately i₀=−1.650 can be used for the third planetary gear set RS3. As the stationary transmission ratio, a value of approximately i_(ST1)=−1.361 is selected for the first spur gear stage ST1, and a value of approximately i_(ST2)=−1.000 is selected for the second spur gear stage ST2. In addition, it arises from the shifting diagram that, for shifting the gears, except for the four gears G4, with which four shifting elements are activated or locked, only three shifting elements are always locked for the other gears.

Specifically, it arises from the shifting diagram in accordance with FIG. 3 that, for the realization of the first forward gear G1, the second shifting element K2 designed as a clutch, the fourth shifting element K4 designed as a clutch, and the fifth shifting element B1 designed as a brake are locked. For the shifting of the second forward gear G2, the second shifting element K2 designed as a clutch, the fourth shifting element K4 designed as a clutch and the sixth shifting element B2 designed as a brake are locked. For the shifting of the third forward gear G3, the first shifting element K1 designed as a clutch, the second shifting element K2 designed as a clutch and the fourth shifting element K4 designed as a clutch are locked. For the shifting of the fourth forward gear G4, the second shifting element K2 designed as a clutch, the third shifting element K3 designed as a clutch and the fourth shifting element K4 designed as a clutch are locked. For the shifting of the fifth forward gear G5, the first shifting element K1 designed as a clutch, the second shifting element K2 designed as a clutch and the third shifting element K3 designed as a clutch are locked. For the shifting of the sixth forward gear G6, the second shifting element K2 designed as a clutch, the third shifting element K3 designed as a clutch and the sixth shifting element B2 designed as a brake are locked. For the shifting of the seventh forward gear G7, the second shifting element K2 designed as a clutch, the third shifting element K3 designed as a clutch and the fifth shifting element B1 designed as a brake are locked. For the shifting of the eighth forward gear G8, the third shifting element K3 designed as a clutch, the fifth shifting element B1 designed as a brake and the sixth shifting element B2 designed as a brake are locked. For the shifting of the ninth forward gear G9, the first shifting element K1 designed as a clutch, the third shifting element K3 designed as a clutch and the fifth shifting element B1 designed as a brake are locked. Finally, for the shifting of the reverse gear R, the first shifting element K1 designed as a clutch, the fourth shifting element K4 designed as a clutch and the fifth shifting element B1 designed as a brake are locked.

With respect to the shifting combinations of the alternative fourth forward gears M1, M2, M3, it is provided that, for the shifting of the alternative fourth forward gear M1, the third shifting element K3 designed as a clutch, the fourth shifting element K4 designed as a clutch and the fifth shifting element B1 designed as a brake are locked. For the shifting of the alternative fourth forward gear M2, the third shifting element K3 designed as a clutch, the fourth shifting element K4 designed as a clutch and the sixth shifting element B2 designed as a brake are locked. Furthermore, for the shifting of the alternative fourth forward gear M3, the first shifting element K1 designed as a clutch, the third shifting element K3 designed as a clutch and the fourth shifting element K4 designed as a clutch are locked.

Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims.

REFERENCE SIGNS

-   1 First shaft as a drive -   2 Second shaft as an output -   3 Third shaft -   4 Fourth shaft -   5 Fifth shaft -   6 Sixth shaft -   7 Seventh shaft -   8 Eighth shaft -   9 Ninth shaft -   11 Transmission housing -   K1 First shifting element as a clutch -   K2 Second shifting element as a clutch -   K3 Third shifting element as a clutch -   K4 Fourth shifting element as a clutch -   B1 Fifth shifting element as a brake -   B2 Sixth shifting element as a brake -   RS1 First planetary gear set -   RS2 Second planetary gear set -   RS3 Third planetary gear set -   SR1 Sun gear of the first planetary gear set -   PT1 Planetary gear carrier of the first planetary gear set -   HR1 Ring gear of the first planetary gear set -   SR2 Sun gear of the second planetary gear set -   PT2 Planetary gear carrier of the second planetary gear set -   HR2 Ring gear of the second planetary gear set -   PT3 Planetary gear carrier of the third planetary gear set -   HR3 Ring gear of the third planetary gear set -   ST1 First spur gear stage -   ST2 Second spur gear stage -   12 Fixed gear of the first spur gear stage -   12A Idler gear of the first spur gear stage -   13 Idler gear of the first spur gear stage -   13A Fixed gear of the first spur gear stage -   14 Fixed gear of the second spur gear stage -   15 Fixed gear of the second spur gear stage -   G1 First forward gear -   G2 Second forward gear -   G3 Third forward gear -   G4 Fourth forward gear -   G5 Fifth forward gear -   G6 Sixth forward gear -   G7 Seventh forward gear -   G8 Eighth forward gear -   G9 Ninth forward gear -   R Reverse gear -   M1 Alternative fourth gear -   M2 Alternative fourth gear -   M3 Alternative fourth gear -   i Transmission ratio -   i₀ Stationary transmission ratios of the planetary gear sets -   I_(ST1) Stationary transmission ratio of the first spur gear stage -   I_(ST2) Stationary transmission ratio of the second spur gear stage -   φ Gear jump 

The invention claimed is:
 1. A planetary multi-speed transmission for a vehicle, comprising: a transmission housing (11); a first shaft (1) provided as a drive (An), and a second shaft (2) provided as an output (Ab) that is arranged axially parallel to the drive (An); a first planetary gear set (RS1), a second planetary gear set (RS2), and a third planetary gear set (RS3); a plurality of additional shafts (3, 4, 5, 6, 7, 8, 9) in addition to the first shaft and the second shaft; six shifting elements (K1, K2, K3, K4, B1, B2), through which the actuation of several gears are realized; machine elements (ST1, ST2) configured to transfer of torque between the drive (An) and the output (Ab); the first shaft (1) connectable, as the drive (An), to a sun gear (SR2) of the second planetary gear set (RS2), to a sun gear (SR1) of the first planetary gear set (RS1), to a planetary gear carrier (PT2) of the second planetary gear set (RS2), to a planetary gear carrier (PT1) of the first planetary gear set (RS1), and to the first machine element (ST1), wherein the first shaft (1) is connectable through a shifting element (K1) designed as a clutch and through a third shaft (3) to the sun gear (SR2) of the second planetary gear set (RS2), whereas the sun gear (SR2) of the second planetary gear set (RS2) is connectable through the third shaft (3) and through a sixth shifting element (B2) designed as a brake to the housing (11); and the second shaft (2), as the output shaft (Ab), is either connected or connectable to the first machine element (ST1) and is connected to the second machine element (ST2).
 2. The planetary multi-speed transmission according to claim 1, wherein the machine elements (ST1, ST2) are defined as either spur gear stages (ST1, ST2) or chains.
 3. The planetary multi-speed transmission according to claim 1, wherein the first shaft (1) is connectable through a second shifting element (K2) designed as a clutch and through a fourth shaft (4) both to the sun gear (SR1) of the first planetary gear set (RS1) and to the planetary gear carrier (PT2) of the second planetary gear set (RS2), whereas the sun gear (SR1) of the first planetary gear set (RS1) and the planetary gear carrier (PT2) of the second planetary gear set (RS2) are connected to each other through the fourth shaft (4).
 4. The planetary multi-speed transmission according to claim 2, wherein the first shaft (1) is connectable through a third shifting element (K3) designed as a clutch and through a fifth shaft (5) both to a fixed gear (12) of a first spur gear stage (ST1) and the planetary gear carrier (PT1) of the first planetary gear set (RS1).
 5. The planetary multi-speed transmission according to claim 2, wherein the second shaft (2) is connected to a fixed gear (15) of a second spur gear stage (ST2), and that the second shaft (2) is connectable through a fourth shifting element (K4) designed as a clutch and through a ninth shaft (9) to an idler gear (13) of a first spur gear stage (ST1).
 6. The planetary multi-speed transmission according to claim 2, wherein the second shaft (2) is connected to a first fixed gear (13A) of a first spur gear stage (ST1) and to a second fixed gear (15) of a second spur gear stage (ST2), an idler gear (12A) of the first spur gear stage (ST1) is connectable through a ninth shaft (9), through a fourth shifting element (K4), through a fifth shaft (5), and through a third shifting element (K3) to the first shaft (1), the third and fourth shifting elements designed as clutches, and the first spur gear stage (ST1) is connectable through the ninth shaft (9), through the fourth shifting element (K4), and through the fifth shaft (5) to the planetary gear carrier (PT1) of the first planetary gear set (RS1).
 7. The planetary multi-speed transmission according to claim 2, wherein a fixed gear (14) of the second spur gear stage (ST2) is connected through a sixth shaft (6) to a ring gear (HR3) of the third planetary gear set (RS3).
 8. The planetary multi-speed transmission according to claim 1, wherein a ring gear (HR1) of the first planetary gear set (RS1) is connected through a seventh shaft (7) to a planetary gear carrier (PT3) of third planetary gear set (RS3).
 9. The planetary multi-speed transmission according to claim 1, wherein at least one of the planetary gear sets (RS1, RS2, RS3) is designed as a negative planetary gear set, and at least one of the planetary gear sets is designed as a positive planetary gear set.
 10. The planetary multi-speed transmission according to claim 1, wherein at least two of the planetary gear sets (RS1, RS2, RS3) are arranged radially relative to each other.
 11. The planetary multi-speed transmission according to claim 10, wherein the second planetary gear set (RS2) and the third planetary gear set (RS3) are arranged radially relative to each other such that the second planetary gear set (RS2) is arranged radially inwardly and the third planetary gear set (RS3) is arranged radially outwardly, the second planetary gear set (RS2) and the third planetary gear set (RS3) connected to each other through a ring gear (HR2) of the second planetary gear set (RS2).
 12. The planetary multi-speed transmission according to claim 11, wherein the ring gear (HR2) of the second planetary gear set (RS2) is connectable through an eighth shaft (8) and through a fifth shifting element (B1) designed as a brake to the housing (11).
 13. The planetary multi-speed transmission according to claim 1, wherein the six shifting elements (K1, K2, K3, K4, B1, B2) are either frictional-locking or positive-locking shifting elements.
 14. The planetary multi-speed transmission according to claim 1, wherein the transmission is shiftable to achieve at least nine forward gears (G1 to G9) and at least one reverse gear (R).
 15. The planetary multi-speed transmission according to claim 14, wherein: a second, a third, and a fourth shifting element (K2, K3, K4) of the six shifting elements are designed as clutches, and a fifth element and a sixth element (B1, B2) of the six shifting elements are designed as a brake; for shifting of a first forward gear (G1), the second shifting element (K2), the fourth shifting element (K4), and the fifth shifting element (B1) are actuated; for shifting of a second forward gear (G2), the second shifting element (K2), the fourth shifting element (K4), and the sixth shifting element (B2) are actuated; for shifting of a third forward gear (G3), the first shifting element (K1), the second shifting element (K2), and the fourth shifting element (K4) are actuated; for shifting of a fifth forward gear (G5), the first shifting element (K1), the second shifting element (K2), and the third shifting element (K3) are actuated; for shifting of a sixth forward gear (G6), the second shifting element (K2), the third shifting element (K3), and a sixth shifting element (B2) are actuated; for shifting of a seventh forward gear (G7), the second shifting element (K2), the third shifting element (K3), and the fifth shifting element (B1) are actuated; for shifting of an eighth forward gear (G8), the third shifting element (K3), the fifth shifting element (B1), and the sixth shifting element (B2) are actuated; for shifting of a ninth forward gear (G9), the first shifting element (K1), the third shifting element (K3), and the fifth shifting element (B1) are actuated; and for shifting of a reverse gear (R), the first shifting element (K1), the fourth shifting element (K4), and the fifth shifting element (B1) are actuated.
 16. The multi-speed transmission according to claim 15, wherein for shifting of a fourth forward gear (G4): the second shifting element (K2), the third shifting element (K3), and the fourth shifting element (K4) are actuated.
 17. The multi-speed transmission according to claim 15, wherein for shifting of a fourth forward gear (M1), the third shifting element (K3), the fourth shifting element (K4), and the fifth shifting element (B1) are actuated.
 18. The multi-speed transmission according to claim 15, wherein for shifting of a fourth forward gear (M2), the third shifting element (K3), the fourth shifting element (K4), and the sixth shifting element (B2) are actuated.
 19. The multi-speed transmission according to claim 15, wherein for shifting of a fourth forward gear (M3), the first shifting element (K1), the third shifting element (K3), and the fourth shifting element (K4) are actuated. 